source : engineeringtoolbox.com

## Hot Air Balloon – Lifting Force

Hot Air Lifting Force

The lifting force from a hot air balloon depends on the density difference between balloon air and surrounding air, and the balloon volume. The lifting force can be calculated as

Fl = V (ρc – ρh) ag (1)

where

Fl = lifting force (N, lbf)

V = balloon volume (m3, ft3)

ρc = density cold surrounding air (kg/m3, slugs/ft3)

ρh = density hot balloon air (kg/m3, slugs/ft3)

ag = acceleration of gravity (9.81 m/s2, 32.174 ft/s2)

Example – Lifting Force created by a Hot Air Balloon

A hot air balloon with volume 10 m3 (353 ft3) is heated to 100 oC (212 oF). The temperature of the surrounding air is 20 oC (68 oF). The air density at temperature 100 oC is 0.946 kg/m3 (0.00184 slugs/ft3) and the air density at temperature 20 oC is 1.205 kg/m3 (0.00234 slugs/ft3).

The lifting force can be calculated as

Fl = (10 m3) [(1.205 kg/m3) – (0.946 kg/m3)] (9.81 m/s2)

= 25.4 N

Weight – or gravity force – can be calculated as

Fg = m ag (2)

where

Fg = weight – gravity force (N, lbf)

m = mass (kg, slugs)

Since lifting force of a flying air balloon equals weight (Fl = Fg) – the lifted mass can be expressed by combining (1) and (2) to

m = Fl / ag

= (25.4 N) / (9.81 m/s2)

= 2.6 kg

The calculation of lifting force can be done in Imperial units as

Fl = (353 ft3) [(0.00234 slugs/ft3) – (0.00184 slugs/ft3)] (32.174 ft/s2)

= 5.7 lbf

Hot Air Balloon – Specific Lifting Force

Specific lifting force (force per unit air volume) created by an hot air balloon – balloon temperature vs. surrounded air temperature – are indicated in the charts below.

SI – units

Imperial Units

Example – Specific Lifting Force from a Hot Air Balloon

If the balloon temperature is 60 oC and the surrounded temperature is -20 oC – the chart indicates a specific lifting force

3.3 N/m3

Hot Air Balloon Lifting Force Calculator

This calculator can be used to calculate the lifting force of a volume with lower density than surrounding air.

balloon volume (m3)

balloon volume density (kg/m3)

surrounding air density (kg/m3)

The ideal gas law – The tank can blow up 884 balloons. Problem: The mass of a hot air balloon and its cargo (not including the air inside) is 200 kg. The air outside is at 10 o C and 101 kPa. The volume of the balloon is 400 m 3. To what temperature must the air in the balloon be heated before the balloon will lift off. (Air density at 10 o C is 1.25 kg/m 3Hot air balloons float in the air because of the difference in density between cold and hot air. In this problem, you will estimate the minimum temperature the gas inside the balloon needs to be, for it to take off. To do this, use the following variables and make these assumptions: The combined weight of the pilot basket together with that ofThe absolute temperature of the hot air at the bottom of the balloon is Th (Where T-Te). The balloon is open at the bottom, so that the pressure inside and outside the balloon is the same. Assume that we can treat air as an ideal gas. Use g for the magnitude of the acceleration due to gravity. For the balloon to float, what is the minimum

(Get Answer) – Hot air balloons float in the air because – A recreational (open) hot air balloon (i.e., Pinside is approximately Poutside) has a volume of 2267 m3 when fully inflated. The total weight of the balloon, basket, ballast and pilot is 1989.4 N (448 lbs). By how much must the density of the air in the balloon be smaller than that of the surrounding atmosphere in order to keep the balloon floating level near the ground?Hot air balloons float in the air because of the difference in density between cold and hot air. In this problem, you will estimate the minimum temperature the gas inside the balloon needs to be, for it to take off. To do this, use the following variables and make these assumptions: The combined weight of the pilot basket together with that of the balloon fabric and other equipment is W. TheIf you heat the air inside the balloon 100 degrees F hotter than the outside air temperature, then the air inside the balloon will be about 25 percent lighter than the air outside the balloon. So a cubic foot of air weighs about 35 grams at 32 degrees F. A cubic foot of hot air at 132 degrees F will weigh 25 percent less, or about 26.5 grams.

Solved: 3. Hot Air Balloons Float In The Air Because Of Th – Please solve w/ an in Celsius, Thanks in adv. Question Details: A hot air balloon achieves its buoyant lift by heating the air inside the balloon, which makes it less dense than the air outside. Suppose the volume of a balloon is 1800m3 and the required lift is 2700N. Calculate the temperature of the air inside the balloon which will produce the required lift.Click here 👆 to get an answer to your question ️ For the balloon to float what is the minimum temperature DarkShadow4343 DarkShadow4343 08.05.2018 Physics Secondary School answered For the balloon to float what is the minimum temperature 2 See answers sairam1919 sairam1919A helium balloon is filled to a volume of 2.88 x 10^3L at 722 mm Hg and 19 degrees Celcius. When the balloon is released, it rises to an altitude where the pressure and temperature are 339 mm Hg and -55vC, respectively. What is . Physics. Hot air balloons float in the air because of the difference in density between cold and hot air.